Sealed push button control switch



May 16, 1961 J. o. ROESER SEALED PUSH BUTTON CONTROL SWITCH F iled Jan. 26, 1959 2 Sheets-Sheet 1 IV I U I I II w 'h Hu '11 H.

May 16, 1961 o, RQESER 2,984,726

SEALED PUSH BUTTON CONTROL SWITCH Filed Jan. 26, 1959 2 Sheets-Sheet 2 I T 1IB I J04 J06 JOE {Li v 102' E 5 INVENTOR.

2%WMM United States Patent SEALED PUSH BUTTON CONTROL SWITCH John 0. Roeser, Park Ridge, Ill., assignor to Illinois Tool Works, Chicago, 111., a corporation of Illinois Filed Jan. 26, 1959, Ser. No. 788,824

12 Claims. (Cl. 200-168) The present invention relates to push button type control switches used on field telephones or other electrical equipment which may be exposed to the weather and to generally dirty environmental conditions. When used in outdoor servce, push button control switches are subject to operational difliculties and sometimes service failures due to the intrusion of dirt, ice, or other foreign materials into interstices which are exposed to the external environment. Some expedients previously used to seal out foreign matter from push button switches have been subject to a number of shortcomings, including imperfect sealing of the structures used and the imposition of resistance to operation of the switches which has detracted from a desirable feel or reaction of the switch to manual actuating forces.

One object of the invention is to provide for use in adverse environmental conditions, such as those encountered outdoors, improved push button switch means which is eifectively sealed in a novel manner against the intrusion of foreign matter.

Another object of the invention is to provide push button switch means, which is effectively protected against the intrusion of foreign matter from the external environment by improved sealing means incorporated into the switch structure in a manner which provides a very desirable feel or reaction of the switch to manual actuating forces.

A more specific object is to provide improved push button switch structure in which a capability of operating reliably in exposed environmental conditions is provided by a novel construction of a very simple and economical character which efiectively excludes foreign matter that could otherwise cause service and operational difficulties.

A further object is to provide sealed push button switch structure, as recited in the previous objects, in which coacting parts are detachably secured in assembled relation to each other by a novel construction of a very simple character which greatly facilitates servicing of the apparatus by inexperienced personnel.

Other objects and advantages will become apparent from the following description of the exemplary forms of the invention illustrated in the attached drawings, in which:

Fig. l is a side View of push button control switch embodying the invention;

Fig. 2 is a right end view of Fig. 1;

Fig. 3 is a sectional view taken along line 3-3 of Fig. 1;

Fig. 4 is a fragmentary sectional view on an enlarged scale taken along the line 44 of Fig. 2;

Fig. 5 is a perspective view of the inner end of switch actuator structure;

Fig. 6 is a fragmentary perspective view of a detachable connecting structure incorporated into the switch assembly;

Fig. 7 is a perspective view showing a switch actuator element with an annular sealattached;

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Fig. 8 is a side view of a modified embodiment of the invention;

Fig. 9 is a right end view of Fig. 8;

Fig. 10 is an exploded perspective view of a normally connected switch block and switch actuator. structure;

Fig. 11 is an end View similar to Fig. 9 but showing the switch block assembly and switch actuator structure disconnected from each other; and

Fig. 12 is a fragmentary sectional view on an enlarged scale taken along the line 12-12 in Fig. 8.

The push button switch unit 20 forming the first embodiment of the invention illustrated in Figs. 1-7 is mounted on a control panel 22 of an instrument intended for outdoor use; such for example, as a field telephone 24 (indicated in phantom in Fig. 1). The switch unit comprises a bushing 26 having an enlarged circular head 28 and an externally threaded shank 30 projecting concentrically from one end of the bushing head through a circular opening 32 in the panel 22.

The bushing head 28 is firmly sealed to the outer or exposed face of the panel 22 by an 'O-ring 34, Fig. 4, seated in an annular groove 36 formed in the head and facing toward the panel in encircling relation to the opening 32. The sealing ring 34 is compressed tightly against the panel 22 by a nut and washer 38 threaded on the shank 3t and engaging the inner face of the panel 22.

The enlarged bushing head 28 is centrally bored from its outer end to define a circular push button well 40 of substantial diameter which is enlarged from its outer end by a counterbore 42 having an axial depth approximately one half that of the button well. An axial bore 44 extends through the bushing 26 from the bottom of the button well 40 to the freeend of the shank 3t} and is enlarged by a deep counterbore 46. Both the bore 44 and the counterbore 46 are coaxial with the button well 40.

The bushing 26 thus formed provides a mounting for a reciprocable switch actuator 48, Fig. 4, comprising a circular push button 50 integral with a plunger 51 concentric with the button 50 and projecting from the inner face of the button through the bushing bore 44.

All foreign matter is sealed out of the space inward of the button well counterbore 42'by means of an annular sealing diaphragm 52 formed of a flat flexible material such, for example, as rubber. The diaphragm 52 has a circular inner periphery 54 which fits into an annular groove 56 encircling the switch actuator plunger 57 be-. tween the inner face of the push button 50 and a circular enlargement 58 of the plunger.

The diameter of the annular groove 56 is somewhat greater than the central opening formed by the inner periphery of theannular seal 52 when the latter is in a normal unstressed condition before being mounted on the switch actuator 4-8. Hence, the inner periphery 54 of the annular sealmust be stretched somewhat to fit around the inner diameter of the groove- 56. For this reason, the annular sealing diaphragm 52 when mounted on the plunger 51, tends to assume a somewhat convex or dishshape, as shown in Fig. 7.

The inner periphery 54 of the annular diaphragm is sealed in the actuator groove 56 not only by the tension Within the diaphragm tending to cause its inner periphery 54 to contract but also by the use of a suitableadhesive or glue to form a bond between this diaphragm and the structure defining the groove 56.

The outer periphery 60, Fig. 4, of the sealing diaphragm 52 fits into the bottom of the button 'well counterbore 42 where it is circumferentially clamped in place by an annual retaining ring 62 pressfitted into this counterbore as shown. A tight seal is formed between the diaphragm" 52 and the encircling bushingstructure by the clamping force of the retaining ring 62 on the diaphragm. Also, adhesive can be applied at this juncture.

The inner periphery of the retaining ring 62 is equal in diameter to the button well 40 and forms an outward Continuation of the well. The outer periphery of the pushbutton 48 is circular and fits closely within the inner periphery of the retaining ring 62. As a matter of fact the outer diameter of the push button 48 is reduced relative to the inner diameter of the encircling ring 62 only to the extent necessary to prevent binding between these parts as the switch actuator 48 is moved axially in operation.

A coil compression spring 64 encircling the actuator plunger 52 between the bottom of the counterbore 46 and the enlargement 58 urges the switch actuator 48 outwardly to a normal position illustrated in Figs. 1, 2 and 4.

Such outward movement of the switch actuator 48 is terminated when the actuator reaches its normal position by engagement with the inner end of the bushing 30 of a split washer 66 secured to the end of the plunger 51 projecting inwardly beyond the bushing as shown in Fig. 4.

It will be noted that when the switch actuator 48 is in its normal position shown in Fig. 4 the inner periphery 54 of the diaphragm 52 is displaced somewhat axially outward of the outer periphery 60 of the diaphragm thus giving the diaphragm a somewhat convex or dish shaped configuration as viewed from the push button end of the switch actuator.

This normal shaping of the somewhat resilient rubber diaphragm 52 together with the previously mentioned stretching of the inner periphery of the diaphragm relative to its outer periphery is of advantage in eliminating resistance by the diaphragm to inward movement of the switch actuator by manual force applied to the push button 50. This flexibility or ease of movement of the diaphragm together with the yiedlable outer force of the spring 64 on the switch actuator 48 provides a very advantageous feel to the switch as sensed by the user when pressing the push button 50.

The only space within the entire unit 20 which is not completely sealed against the external environment is the very small annular space between the inner face of the push button 50 and the resilient diaphram 52. Even this space is so effectively shielded by the close, substantially sliding fit of the push button 50 within the encircling ring 62 that all foreign bodies are as a practical matter excluded.

Moreover, the stretchable character of the rubber diaphragm 52 eliminates serious interference with operation of the push button 50 by any moisture which might get into the space between the diaphragm and the inner face of the push button.

The inner end of the switch plunger 52 is used to operate a battery or series of individual control switches 68 mounted in a switch block 70, Fig. 1. The switch block 70 includes a U-shaped support frame 72 of sheet metal which is detachably secured to the inner end of the bushing shank 30 in an improved manner which facilitates connection and disconnection of the switch block and its support by even experienced service personnel.

As shown in Figs. 4 and 6 a fiat plate portion 74 of the frame 72 defines an elongated generally rectangular opening 76 dimensioned to provide for passage therethrough of a transverse retaining element 78 on the inner end of the bushing 26.

The retaining element 78 is similar in shape to but slightly smaller than the opening 76. Opposite ends of the retaining elements 78 in effect form a pair of diametrically opposed lugs 82, 84 projecting radially outward beyond a neck 85 connecting the retaining element 78 to the adjacent portion of the bushing shank 30. The action of these lugs in supporting the switch block 70 will be explained presently.

Having reference to Figs. 4 and 5, a pair of opposing cantilever leaf spring elements 86, 88 project toward each other into overlapping relation to opposite ends of the opening 76 in the frame plate 74. These spring elements are formed as integral portions of the plate 74 by slitting the plate along opposite sides of each spring to be formed.

To attach the switch block 70 to the sealed bushing 26 the frame plate 74 is turned to orient the opening 76 longitudinally with the retaining element 78 and the plate is moved toward the bushing. The two lugs 82, 84 of the retaining element 78 press against the projecting ends of the springs 86, 88 to swing the latter downwardly below the plate 74 as shown in Fig. 4, until the lugs 82, 86 underlie the plate 7 4. Then the switch block 7 0 is rotated one quarter turn to lock the lugs 82, 84 below the plate 74 at opposite sides of the opening '76.

As shown in Figs. 4 and 6 the extreme ends of the springs 86 and 88 are shaped to form downwardly offset steps 90, 92 which normally fit against opposite sides of the retaining element 78 to yieldably, yet effectively, hold the switch block 70 against rotation from its mounted position on the bushing 28. However, the manual application of rotary force to the switch block 70 causes the lugs 82, 84 to cam the spring elements 86, 88 downwardly to allow rotation and hence dismounting of the switch block.

It will be noted that the inner end of the switch actuator plunger 52 engages a pivoted plate 97 in the switch block 70. This plate transmits inward motion of the push button 50 to switch actuating plungers 99 for the respective control switches 68.

Concentric grooves 93 formed in the pushbutton 50, Fig. 4, provide a pleasing appearance, particularly when the grooves are colored.

In the modified embodiment of the invention illustrated in Figs. 8-12 component elements corresponding to elements previously described in connection with the first embodiment illustrated in Figs. 1-7 are designated by the same reference numerals with the addition of the suffix a.

This second embodiment of the invention differs from the first principally in the means for mounting the somewhat dilferent switch block 100 on the inner end of the bushing shank 30a. This switch block includes a plurality of switches operated by a plunger 102 in the block.

A pair of resilient support plates 104, 106 secured to opposite sides of the switch block 100 project upwardly beyond the block in opposing parallel relation to each other, as shown in Figs. 9 and 10. Two releasing tabs 108, 110 struck out of the respective support plates 104, 106 extend from the projecting ends of the plates toward the block 100 in diverging relation to each other. The application of a manual squeezing force to the projecting ends of the tabs 108, 110, as indicated by the arrows 112 in Fig. 11, serves to swing the extreme ends of the two plates away from each other.

The projecting marginal edges of the respective plates 104, 106 are turned toward each other to form retaining flanges 114, 116 for engaging the bushing neck 85a above the retaining element 78a, Fig. 11. Shallow arcuate notches 118, 120 out into the respective flanges 114, 116 provide clearance for the bushing neck 85a allowing the plate flanges 114, 116 to fully embrace opposite sides of the retaining elements 78a, as shown in Figs. 9 and 12, to provide a firm support for the switch block 100. The switch plunger 102 in the block 100 is engaged and actuated by the inner end of the switch actuating plunger 51a.

To remove the switch block 100 from its normal mounted position or to remount the block in its normal position it is necessary merely to apply squeezing force to the two tabs 108, 110, Fig. 11, as previously mentioned thus swinging the retaining elements 114, :116 away from each other to move past the retaining element 78a.

It will be understood that this invention is not necessarily limited to the construction of the specific embodiments disclosed but includes variations and modifications within the spirit and scope of the invention as defined by the appended claims.

The invention is claimed as follows:

1. Sealed push button switch actuating means for field telephones and the like, comprising in combination, a bushing defining a counterbored button well at one end thereof and having a threaded shank extending to the other end thereof, said bushing defining a counterbored axial bore extending through said shank from the bottom of said button well, a reciprocable switch actuator including a circular button located in the counterbored end of said well and a switch actuating plunger integral with said button and extending through said axial bore beyond said shank, means on said plunger engageable with said bushing to limit movement of said actuator in the direction of said button, said actuator defining an annular groove at the juncture of said plunger and said button; an annular sealing diaphragm of flat, flexible material having an inner periphery defining a circular opening having a normal diameter slightly less than the inner diameter of said groove; said inner periphery of said diaphragm being fitted into said groove and forming a tight seal with said actuator, said diaphragm having an outer periphery clamped in the counterbored outer end of said well by an annular retaining ring having an inner periphery encircling and forming a close radial fit with the periphery of said button, and a compression spring mounted in said counterbored axial bore and acting against the plunger side of said button.

2. Sealed pushbutton switch actuating means for field telephones and the like, comprising in combination, a bushing defining a counterbored button well at one end thereof and having a threaded shank extending to the other end thereof, said bushing defining an axial bore extending through said shank from the bottom of said button well, a reciprocable switch actuator including a circular button located in the counterbored end of said well and including a plunger integral with said button and extending through said axial bore beyond said shank, spring means urging said actuator in the direction of said button end thereof, said actuator defining an annular groove at the juncture of said plunger and said button, an annular sealing diaphragm having an inner periphery defining a circular opening having a normal diameter slightly less than the inner diameter of said groove, said inner periphery of said diaphragm being stretched and fitted into said groove to form a tight seal with said actuator, said diaphragm having an outer periphery clamped in the counterbored outer end of said well by an annular retaining ring having an inner periphery forming a close radial fit with the periphery of said button, and means for terminating movement of said switch actuator by said spring means in a normal position in which said inner periphery of said diaphragm is displaced somewhat from said diaphragm outer periphery in the direction of said push button.

3. Externally sealed switching means comprising, in combination, a mounting bushing having an enlarged head integral with a threaded mounting shank extending from the head, said head including means encircling and defining a button well opening away from said shank, an axial bore extending through said shank from said well, a switch actuator including a button having a close fit within the outer end of said well and a plunger extending through said bore, an annular seal of generally flat flexible material having an inner periphery encircling and sealed to said actuator at the plunger side of said button, said means encircling and defining said button well including means forming 'a tight circumferential seal with the outer periphery of said diaphragm, a pair of retaining lugs formed on the end of said bushing shank opposite from said head and projecting radially outward in diametrically opposed relation to each other, a switch block having a housing defining an elongated opening therein shaped to permit passage therethrough of said lugsand having a width less than the distance between opposite ends of the lugs whereby said housing is secured to said bushing upon insertion of said lugs through said opening: and rotation of said housing relative to said bushing, a pair of leaf spring elements on said housing projecting beyond opposite ends of said opening for engagement with said lugs upon insertion of the latter through said opening, and switch means in said block operated by the adjacent end of said plunger.

4. Sealed push button switching means comprising, in combination, a bushing including a shank extending from a head defining a button well opening away from the shank, said bushing defining an axial xbore extending through said shank from said well, a switch actuator including a button having a close fit within said well and a plunger extending through said bore, an annular seal of generally fiat flexible material having an inner periphery encircling and sealed to said actuator at the plunger side of said button and having an outer periphery sealed to the periphery of said button well, a retaining element on the free end of said shank having a noncircular, transverse configuration, a switch block including a support therefor defining a noncircular opening therein dimensioned to permit passage therethrough of said retaining element and to provide a support for said block on said shank upon movement of said retaining element through the opening and rotation of the block relative to said bushing, and control switch means in said block operated by said plunger.

5. Sealed push button switching means comprising, in

combination, a bushing defining a button well at one end.

thereof and having an axial bore extending from the but-, ton well to the other end of the bushing, a switch actuator including a push button having a close fit within said button well and including a plunger extending through said axial bore, an annular seal having an inner periphery encircling and sealed to said switch actuator and having an outer periphery circnmferentially sealed to the periphery of said button well, a control switch block, means detachably securing the switch block to the end of said bushing opposite from said well, and said switch block including control switch means operated by said plunger.

6. Sealed push button switching means as recited in claim 5 in which the means for detachably securing the switch block to the bushing comprises a noncircular retaining element on the bushing and a pair of opposed, cantilever plates projecting from the switch block to yieldably engage opposite sides of said retaining element.

7. Sealed push button switching means comprising, in combination, a bushing defining a button well at one end thereof and having an axial bore extending from the button well to the other end of the bushing, a switch actuator including a push button having a close fit within said button well and including a plunger extending through said axial bore, an annular seal having an inner periphery encircling and sealed to said switch actuator and having an outer periphery circumferentially sealed to the periphery of said button well, a retaining element on the end of said bushing opposite from said well, a control switch block, a pair of opposed cantilever plates of flexible construction projecting from said switch block and having means at the outer ends thereof adapted to engage opposite sides of said retaining element, a pair of releasing tabs connected to the projecting ends of said respective cantilever plates and extending toward said switch block in diverging relation to each other to etfect movement of the projecting ends of said cantilever plates away from each other to effect disengagement of said cantilever plates from said retaining element upon movement of the free ends of said tabs toward each other, and control switch means in said switch block operated by said plunger.

8. Sealed push button switch actuating means, comprising, in combination, a bushing defining a button well at one end thereof and having a shank extending to the other end thereof, said bushing defining an axial bore extending through said shank from said button well, a reciprocable switch actuator including a circular button located in said button well and including a plunger integral with said button and extending into said axial bore, spring means urging said actuator in the direction of said button end thereof, an annular sealing diaphragm encircling said plunger adjacent said button and having an inner periphery tightly sealed to aid actuator in a stationary position in relation to the actuator, said diaphragm having an outer periphery tightly clamped to said bushing by an annular retaining ring having an inner periphery extending into engagement with said diaphragm and forming a close radial fit with the periphery of said button whereby the annular portion of said diaphragm which extends radially beyond said button is permanently held stationary with respect to said bushing, and means for terminating movement of said switch actuator by said spring means in a normal position in which said inner periphery of said diaphragm is displaced somewhat from said diaphragm outer periphery in the direction of said push button.

9. Sealed push button switch actuating means comprising, in combination, an immovable mount, said mount including structure shaped to define an outwardly open circular button well, a switch actuator including a button disposed in said well to move freely along the axis thereof and including a plunger secured to the inner face of said button and projecting inwardly into said mount, a flexible sealing diaphragm of annular form encircling said plunger adjacent said button and having an inner periphery smaller in diameter than the diameter of said button, means forming a sealed connection between the inner periphery of said diaphragm and said actuator in which the inner periphery of the diaphragm is secured in a stationary position in relation to the actuator, means immovably joining the outer periphery of said diaphragm to said mount structure encircling and defining said button well, and said well being formed by said mount structure to have a minimum diameter outwardly of said diaphragm which is at least equal to the diameter of the innermost portion of the periphery of the diaphragm which is immovably joined to said mount structure.

10. Sealed switch actuating means comprising, in combination, a mount including structure forming an internal cylindrical wall defining an outwardly open cylindrical button well, a switch actuator including a switch actuating button disposed in said well and being shaped and dimensioned to define a circular periphery having a close fit with said cylindrical well wall, said actuator including a plunger element extending into said mount from the inner face of said button, a flexible diaphragm of annular form having an inner periphery immovably joined to said actuator radially inward from the periphery of said button, means forming a sealed immovable connection between the outer periphery of said diaphragm and said mount which extends radially inward into flush alinement with said well wall, and spring means coacting with said actuator to urge the latter longitudinally in the direction of the button end thereof.

11. Sealed switch actuating means comprising, in combination, a reciprocable switch actuator including a plunger element and a push button on one end of said plunger element, a stationary mount encircling said actuator and receiving said plunger element for reciprocation of the latter relative to said mount, an annular sealing diaphragm encircling said actuator at the plunger side of said button and having an inner periphery sealed to said actuator in a stationary position relative to the actuator, said mount including means encircling said actuator and engaging the outer periphery of said diaphragm to circumferentially join the latter to said mount in an immovable position in relation to the mount, and the entire structure of said mount located on the button side of said diaphragm having an innermost radial extremity which is limited to a flush radial alinement with the radially innermost portion of the outer periphery of said diaphragm which is immovably joined directly to said mount.

12. Sealed switch actuating means comprising, in combination, a reciprocable switch actuator including a plunger element and a push button on one end of said plunger element, a stationary mount encircling said actuator and receiving said plunger element, an annular sealing diaphragm of substantial radial width encircling said actuator at the plunger side of said button and having an inner periphery sealed to said actuator in an immovable position in relation to the actuator, said mount including annular clamping means clamping the outer periphery of said diaphragm immovably to said mount, the entire stationary structure of said mount including said clamping means located on the button side of said diaphragm having an innermost radial extremity which is limited to a flush radial alinement with the radially innermost extremity of the outer periphery of said diaphragm which is directly engaged by and held against movement by said clamping means, and said button being dimensioned to extend radially outward into close circumferential proximity to said clamping means.

References Cited in the file of this patent UNITED STATES PATENTS 1,903,135 Rees Mar. 28, 1933 2,357,973 Robbins Sept. 12, 1944 2,883,496 White Apr. 21, 1959 

